Activity Coefficient Measurements and Thermodynamic Modeling of (CaCl₂ + l-Alanine + Water) System Based on Potentiometric Determination at T = (298.2, 303.2, and 308.2) K

Abstract

In this work, the thermodynamic properties of the ternary (CaCl 2 + L-alanine + water) system, using the potentiometric method, were reported. The potentiometric measurements were performed on the galvanic cell of the type: and 0.4 mol•kg −1 of L-alanine, over total ionic strengths from 0.0100 mol•kg −1 to 3.0000 mol•kg −1 at T = (298.2, 303.2, and 308.2) K and P = 0.1 MPa. The Ca−ISE was prepared in our laboratory using the ionophore treated by carbon nanotubes. The Debye−Huckel extended equation, Pitzer ion interaction and PSC models were used to correlate the experimental data. The unknown parameters were evaluated and utilized to calculate the thermodynamic properties such as the mean activity coefficients, the osmotic coefficients, the solvent activity, and the excess Gibbs free energy for underinvestigated electrolyte solutions.

Thermodynamic Study of (KCl + N,N-Dimethylformamide + Water) System Based on Potentiometric Measurements

“…To prepare the potassium ion selective electrode (K-ISE), the polyanetholesulfonic acid sodium salt was used as the ionophore according to our previous works. ,, The optimized amounts of 5.1 mg of additive KTPClPB, 58 mg of plasticizer DBP, and 28.9 mg of powdered PVC in 1.2 cm 3 of dry freshly distilled THF was used to this aim. The ISE preparation method was entirely described in our previous work . Also, the Ag–AgCl wire electrodes were made ready by the electrolysis technique, as described in ref .…”

“…The cell potential measurements were carried out to determine the activity coefficients for KCl in the ternary system (KCl + DMF + H 2 O). The standard addition procedure was performed to measure the cell potential data according to previous work …”

“…The ISE preparation method was entirely described in our previous work. 25 Also, the Ag−AgCl wire electrodes were made ready by the electrolysis technique, as described in ref 31. The Ag− AgCl electrodes were used as both chloride-selective electrodes and internal reference electrodes.…”

“…Among the experimental techniques, such as potentiometric method, , isopiestic vapor pressure, and other measurements, , the former method is more used to study the thermodynamic properties of electrolyte solutions. The cell potential method presents advantages such as rapidity, stability, and relative simplicity to generate experimental data with regard to the other methods. , …”

Thermodynamic Properties Determination and Modeling of the (CaCl2 + Ca(NO3)2 + l-Glutamine + H2O) System Using Potentiometric Measurements at T = (293.2, 303.2, and 313.2) K

“…To measure the thermodynamic properties in mixed electrolyte solutions, the most common methods involve the isopiestic vapor pressure, , vapor pressure lowering, , the potentiometric techniques, , and hygrometric method. , Among the various methods, the potentiometric method is proper because of rapidity and relative simplicity to generate experimental data in comparison with the other techniques. , …”